Modular system for connecting multiple customer premises voice and data communications devices to a T1 data line

ABSTRACT

An integrated system concurrently connects voice and data communications devices used by small and medium sized businesses to a network T1 data line terminating at the customer premises. A system chassis includes multiple slots and backplane connectors for removably receiving a bank controller unit (BCU), power service unit (PSU), and one or more different types of smart and dumb voice and data access modules that provide the functional interface to the customer premises equipment. The BCU controls the operation of the system, which can be configured by the customer through an external terminal interface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/834,988, filed on Apr. 13, 2001, now U.S. Pat. No. 7,185,115 issuedFeb. 27, 2007 and entitled “Modular System for Connecting MultipleCustomer Premises Voice and Data Communications Devices to a T1 DataLine,” which is a non-provisional patent application of U.S. ProvisionalPatent Application No. 60/197,236, filed on Apr. 14, 2000 and entitled“Modular Systems for Connecting Multiple Customer Premises Voice andData Communications Devices to a T1 Data Line.”

BACKGROUND OF THE INVENTION

The present invention relates in general to voice and datacommunications systems, and is more particularly directed to systems forproviding integrated voice and data access to a T1 carrier data lineterminating at the customer premises.

Providers of voice and data communications services frequently provide aconnection to their customers' premises using a T1 circuit. The term “T1circuit” is commonly used to identify a multiplexed 24 channel, 1.544Mbps digital data circuit providing communications between twofacilities or from a local service provider to a customer. “T1” refersto the transport of a DS1 formatted signal over a copper, fiber orwireless medium for deploying voice, data or video-conferencingservices. The ‘T’ designation refers the bit rate and the coppertransmission system and the ‘DS’ designation refers to the bit formatand framing. However, many times the terms are used interchangeably. Asingle 64 kbps channel is called a DSO. The T1 rate of 1.544 Mbps forproviding 24 channels of 64 kbps each is referred to as a “DS1.”

The T1 circuit is part of an extensive digital communications hierarchythat starts with 24 DSO's at 64 kbps each. These individual DSO's areused to provide voice or digital data to support point-to-point ornetwork applications. By combining multiple DSO's, a high-speedinterface can be provided to support a synchronous interface to a LocalArea Network (LAN) router or voice PBX. For distances longer than onemile, a repeater is placed every mile to regenerate the signal.

As competition for providing dial tone and bandwidth to customersincreases, communications service providers must find integrated accessdevices that allow cost-effective deployment of voice and data servicesat the customer's premises. Many T1 service customers will have avariety of different voice and data hardware devices and communicationssystems installed at the customer premises, each of which must share aconnection to a single T1. Examples of customer premises communicationsdevices that may require a concurrent interface to network T1 include:

-   -   analog telephone devices, requiring Foreign Exchange Office        (FXO) and/or Foreign Exchange Subscriber (FXS) interfaces;    -   network routers, bridges, switches; and codecs (coders/decoders)        used in audio broadcast and video conferencing systems; each        having standard V.35 DTE (Data Terminal Equipment) interface        connections;    -   Four wire DDS (Digital Data Service) devices, such as a CSU/DSU        (Channel Service Unit/Data Service Unit) for connecting to a WAN        (Wide Area Network);    -   ISDN (Integrated Services Digital network) devices; and    -   Fractional T1 communications.

Conventional integrated T1 access devices may combine all of thisfunctionality into a single unit that is not scaleable, meaning that thecustomer must often purchase a system having more functionality and moreinterface components into the device than the customer initially needs.Also, the requirements of the customer may change after the T1integrated access unit is purchased. Because conventional integratedaccess devices are typically supplied with a hardware and interfaceconfiguration that is fixed internally, a change in customer needs mayresult in a costly internal re-configuration or equipment replacementdecision by the customer. While a re-configuration takes place to add anew interface component, for example, the entire access unit must bedisabled, thereby disrupting all of the customer communications systemsthat share the T1. In other words, it is difficult for the customer to“mix and match” the access device interfaces to the customer's differentcommunications hardware as the customer's needs change after the accessunit is purchase and initially configured. In fact, many conventional T1integrated access devices cannot under any circumstances serve all ofthe customer's voice and data applications at the same time.

Another undesirable characteristic of conventional integrated accessdevices is the expense associated with the design of the differentcomponents that provide the interface to the different customer premisesdevices described above. Often, each of these interface components willbe “smart”, having its own processor or other similar hardware andsoftware to provide a high degree of ‘stand alone’ control of theoperations of that interface component. The combined presence of thisredundant processing power within each interface component of theintegrated T1 access unit increases the total cost of purchase andownership and may increase the complexity of device control andmanagement.

In many applications where T1 access devices are installed at thecustomer premises, there is a need for a separate AC power supply topower the device as well as an auxiliary battery back-up system toprotect the operation of critical communications devices that areconnected to the T1 in the even of a power failure. There are a widevariety of conventional AC power supplies and back-up systems availablefor this purpose. A block diagram of a typical combination AC powersupply and battery backup system 100 used in the prior are, is shown inFIG. 13 A conventional rectification and power conditioning section 101has two outputs as shown. The first output (output 1) is connected to anelectronic system (such as a T1 access system) to provide power to thesystem during normal operation. The first output is also linked to abattery monitoring and back-up relay control circuit 102. Themonitoring/control circuit 102 monitors the first output to determine ifthe voltage being supplied to the electronic system is within specifiedparameters for the electronic system and, if not, sends a signal to thenormally-open relay circuit 103 to switch the battery 104 into the powercircuit to the electronic system. The second output (output 2) is usedto maintain a charge on the battery 104 and is connected to the battery104 and opens the normally closed relay 106 when the battery electricalparameters deviate from normal.

There are several weaknesses in the typical prior art system 100 asillustrated in FIG. 13. First, because the rectification/conditioningsection 101 must have two separate outputs, the complexity (e.g., partscount) of the section is increased which can add to the overall allexpense of the system 100. Second, the separate charge limiting circuit105 also increases the component count and power dissipations of thesystem 100. Third, the battery back-up function of the prior art system100 is not entirely automatic because the battery 104 is not connectedto the electronic system during normal operation. Rather, the monitoringand relay circuit 102 must be used to close the relay circuit 104 whenan abnormal condition is detected at output1.

Accordingly, there is a need for a low cost, easy to use system forallowing a small business customer to send and receive voice and datatraffic over a single T1 terminating at the customer's premises.Preferably such a system will be scalable and easily re-configured toadapt to different communications needs of the customer. In addition,there is need for an improved and lower cost AC power supply and batteryback-up system to power T1 interface devices as well as othercommunications equipment.

SUMMARY OF THE INVENTION

The system of this invention is a low-cost integrated T1 access device,allowing service providers to offer combined voice and data traffic overa single T1 terminating at a small or medium size business customer'spremises. The system supports a broad series offering including analogvoice (FXO/FXS), NxData, fractional T1, ISDN and DDS.

In one embodiment, the system provides six slots in a single systemchassis for the customer to combine a variety of voice and data servicesaccess modules based on the specific requirements of each application.In one embodiment, up to six quad FXS or FXO access modules havingautomatic gain adjustment provide up to 24 analog voice lines. TR-08capability allows connection directly to the central office switch.

Data options include a fractional T1 port, as well as DDS, ISDN, andNx56/64 access modules. The fractional T1 drop-and-insert port on therear of the system chassis provides a convenient method of dropping anumber of DSO's to a PBX or other equipment via a DSX-1 signal.

The system, including the access modules, is controlled and supervisedby a bank controller unit (BCU) having an internal processor connectedto an external terminal interface that can be used for system managementand testing. The BCU also includes an integral T1 channel service unit(CSU) for terminating the network T1 and allowing outside plant (OSP)cabling. Optionally, the BCU will also incorporate a fractional T1interface. The BCU internal processor allows it to control and supervise“dumb” access modules (those without processors), further lowering thetotal cost of the system.

System power is provided by a chassis mounted power service unit (PSU)that allows the system to be powered from the central office signal. Ina preferred embodiment, the PSU also supplies ring generation for anyanalog telephones (POTS) connected to the system through an FXS accessmodule. Optionally, the system may be configured with an AC power supplyand mounted to the exterior of the system chassis and battery back-upunit. The AC power supply has a reduced complexity and component countand the battery back-up unit is entirely automatic because the batteryis connected to the system during normal operation.

The architecture of the system facilitates cost-efficient growth orchange in the communications needs of the small or medium size businesscustomer. Because the provider only installs the number of voice portsneeded for the customer's application, initial turn-up costs are lowerbecause the provider can defer access module cost until it is needed. Indata applications, the system provides the flexibility to mix voice anddata units also based on the particular requirements of each customerapplication.

When maintenance becomes necessary, the system design allow techniciansto reach the access modules, BCU, power supplies and battery back-upsystem easily. Access modules are hot swappable and accessible at alltimes. An individual access module may be replaced without disruptingother modules and services. The quad FXS/FXO access module designensures that a maximum of only four analog circuits are affected whenreplacing an access module.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram that illustrates the various local loop accessoptions that are selectable by the customer for using the system of thepresent invention to connect multiple voice and data communicationsdevices at the customer premises to an incoming T1 line, further showingthe system network and system management interfaces.

FIG. 2 is a block diagram that illustrates the use of a Nx56/64 DTEaccess module in the system of this invention to connect customerpremises V.35 DTE devices to the provider network through an incoming T1line.

FIG. 3 is a block diagram that illustrates the interconnection over a T1of two systems, with each system providing an interface to diversecustomer premises voice and data communications devices.

FIG. 4( a) is a block diagram showing use of the system of thisinvention to connect a conventional analog telephone (POTS) at thecustomer premises to a central office switch through an incoming T1 lineby using Foreign Exchange Office (FXO) and Foreign Exchange Subscriber(FXS) access modules.

FIG. 4( b) is a block diagram showing use of the system of thisinvention to connect a conventional analog telephone (POTS) at thecustomer premises to a central office switch over an incoming T1 line byusing a Foreign Exchange Subscriber (FXS) access module operating in aTR-08 signaling mode.

FIG. 5 is a front perspective view of the system chassis structure ofthis invention showing the front panel portions of the bank controllerunit, power service unit, and further showing multiple access modulesinserted into module slots in the system chassis.

FIG. 6 is a perspective view of a single access module which could bereceived within the system chassis structure shown in FIG. 5.

FIG. 7 is an exploded perspective view of the system chassis structureof FIG. 5.

FIG. 8 is a perspective view of the system chassis structure of FIGS. 5and 7 mounted to an optional battery box and further showing andoptional AC power supply mounted to the side of the system chassis.

FIG. 9 is a schematic diagram of the electrical components of the systemchassis, showing the electrical connections for the bank controllerunit, the power service unit, and the chassis slots for acceptingmultiple access modules.

FIG. 10 is a block diagram of one embodiment of a bank controller unitfor use in the system of the present invention.

FIG. 11 is a block/schematic diagram of the Bank Controller Unit used inone embodiment of the system.

FIGS. 12( a), 12(b), and 12(c) are collectively a block/schematicdiagram of a quad FXS access module that can be used in an embodiment ofthe system of this invention.

FIG. 13 is a block diagram of a typical AC power supply combined with abattery back-up system that is used in the prior art to powercommunications devices and systems, including T1 integrated accesssystems.

FIG. 14 is a block diagram of the AC power supply and battery back-upsystem used in the system of the present invention.

FIG. 15 is a simplified schematic diagram of one embodiment of the ACpower supply and battery back-up system of FIG. 14.

FIG. 16 is a timing diagram for SPI receive status interface with allaccess modules (8 bits) data coming from access module.

FIG. 17 is a timing diagram for SPI receive interface from smart accessmodules for provisioning (9 bits) data going into access module.

FIG. 18 is a timing diagram for SPI transmit interface to smart accessmodules for provisioning (9 bits) data coming from access module.

FIG. 19 is a timing diagram for T1 interface (zoomed in).

FIG. 20 is a timing diagram for T1 interface (zoomed out).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As a starting point in understanding the modular structure and operationof the integrated access system of the present invention, FIG. 1conceptually illustrates the use of the system 10 in conjunction withvarious local loop, network, and management interfaces. Morespecifically, FIG. 1 shows a central office (CO) switch connected to thesystem 10 (and system chassis 11) through a DS1 (T1) line thatterminated at the customer premises, which is where the system isinstalled. System functions are controlled by a Bank Controller Unit(BCU) that includes an RS-232 terminal interface accessible though afront panel connector, allowing the customer to control the system 10from a VT100 terminal. FIG. 1 further shows the different types of voiceand data communications devices that can be located at the customerpremises and functionally connected to the T1 through one or morediscrete access modules removably connected to system chassis 11. Thecustomer premises equipment examples shown include: Up to 24 analogtelephones (POTS) through one or more FXS/FXO access modules; a PBXthrough a system fractional T1 port; a router or videoconferencingsystem through a Nx56/64 access module to establish a V.35 DTEconnection; an ISDN terminal adapter through a U-BRITE access module;and a DSU/CSU through a 4-wire DDS access module.

FIGS. 5, 6, and 7 provide more detailed information about the mechanicalconfiguration of the system chassis 11 and the removable connection ofthe system modules 12, 14, 16. A series of backplane connectors 66 arearranged laterally along a rear panel 64 of chassis 11 to define aseries of seven slots 72, 74 and a chassis backplane that is arrangedelectrically as shown in FIG. 9. Accordingly, each system module 12(generically illustrated in FIG. 6) will be mechanically implemented ona circuit card on which the various module components are mounted, andincluding a rearwardly projecting edge connector 63 that mechanicallyand electrically engages a corresponding backplane connector 66 when themodule is inserted into a slot 72.

The BCU and a Power Service Unit (PSU) are common system modules thatare used in each application of the system 10 and occupy two of thechassis slots 72, electrically represented as BCU slot and PSU slot onFIG. 9. The seven remaining slots 72 (having slot backplane connectors66 electrically represented on FIG. 9 as slots 1-7) are available toreceive the various access modules 12, with slots 6 and 7 dedicated toaccept a Nx56/64 DSU access module.

As shown on FIG. 9, the system chassis 11 further include externalelectrical connectors for interfacing with the network T1 or DS1(connectors 31, 32), optional fractional T1 (connector 33) and acustomer terminal interface (connector 34). Preferably the network andfractional T1 connectors 31, 33 are modular RJ-48C connectors. The pinson each of the slot 1-7 connectors shown on FIG. 9 (connectors 66 onFIG. 7) provide connections to the various system backplane power,Serial Peripheral Interface (SPI), and data buses used by the BCU, PSU,and access modules. These are described in more detail below.

Bank Controller Unit

The Bank Controller Unit (BCU) provides the control functions for thesystem 10 including backplane signal generation and control. The BCUcontrols all of the functions of the voice (FXS and FXO) access modulesand provides supervisory control over the power service unit (PSU). TheBCU also provides provisioning/test control for any “smart” accessmodules (i.e., access modules that have their own processor) such as theNx56/64, OCU DP, DSO-DP or U-BRITE access modules. The FXS and FXOmodules are sometimes referred to as “dumb” modules because they mustrely exclusively on the BCU for control and supervision.

The basic architecture and interconnection of the components andsub-systems of the BCU are shown in FIGS. 10 and 11. The BCU iscontrolled primarily by an 8-bit 8032 microprocessor 41. The network T1is connected through the T1 connector 31 (FIG. 9) to a T1 interfacecircuit 42 that includes a CSU. Interface transceiver 42 can be aconventional device such as a Dallas Semiconductor DS2152 integratedcircuit. An optional fractional T1 interface transceiver (43 on FIG. 10but not shown on FIG. 11) can also be included and can also be a DS2152IC. System program and data memory is provided by 32 Kbytes of RAM 44,and 2 Mbytes of FLASH ROM 45, connected to processor 41 though octallatch 60. The BCU firmware provides all call control, test setup, andprovisioning for the FXS and FXO access modules. Quad multiplexer 61 isused to download new programming to FLASH ROM 45. The BCU can beprovisioned via DIP switches 46 or via the terminal interface throughthe front panel DB-9 admin connector 34 (FIG. 9). Bit and byte clock isalso available via the DB-9 front panel connector 34, compatible with aTPI 108/109 test set.

The BCU also drives status LED's 47 on the front panel to indicate thestate of the main network T1 interface (and fractional T1 if installed).T1 performance monitoring information is maintained and processed by theBCU for the network T1 interface (and optionally for the fractional T1).Performance monitoring information is available to the network via theFDL in ESF mode and through the terminal interface. Preferably, the BCUwill include 4096 bits of non-volatile storage in an EEPROM 48. Circuit62 provides watch dog and power reset functions.

Each module slot 74 in the chassis 11 can be selected by the BCU overSPI interface 49. In a preferred embodiment, there are seven differentmodule selects (PSU & Slots 1-6) as well as two additional selects thatare common to each slot for selecting different registers/chips on agiven access module. The BCU controls all aspects of operation of thesystem 10. As mentioned above, the system services provide by the BCUinclude: network and fractional T1 control; access module control; alarmcontrol; a user interface; and a backplane control. A field programmablelogic array (FPGA) 50 in the BCU provides the clock generation, chipselect, and backplane interface functions. The backplane databus/interface 59 also connects the FPGA 50 to the other system modules.MCAN oscillators 52,53 provide timing signal for FPGA 50. The BCU alsoincludes a composite clock input to the FPGA 50. A composite clockinput/output termination 54 c (FIG. 9) is provided on the system chassis11.

BCU Network and Fractional T1 Control

The BCU operates both the network and fractional T1 interfaces.Performance monitoring and alarm information is maintained for both thenetwork and fractional T1 services. The BCU supports many different T1including Extended Superframe (ESF), Superframe (SF), TR-08 withalarm-16, and TR-08 with alarm-13. These formats can run over either anAMI or B8ZS line code. The network and fractional T1 ports runindependently of each other.

The BCU maintains performance information for both the network andfractional T1 interfaces for the current and most recent twenty-fourhour period. The parameters stored are Errored Seconds (ES), SeverelyErrored Sec (SES), Severely Errored Frame (SEF), Frame Sync Bit Errors(FS), Line Code Violation (LCV), and Slip Event (SLP).

Access Module Control

In accordance with one of the novel aspects of this invention, the BCUcan concurrently control and supervise many different types of accessmodules 12, 14, 16 including FXS/DPO, quad FXO, Nx64/56, OCU DP, DSO DP,and U-BRITE (ISDN) modules. Conventional components and circuits used tointerface and connect voice and data customer premises equipment to anetwork T1 are well known and available. Such circuits and componentscan be used in the system of this invention if modified to include abackplane (e.g., edge) connector through which physical mounting, powerdistribution, and signaling in conformity with the bus structure of thesystem backplane can be provided. In addition, the access modules 12will typically include a bus transceiver to interface the backplane buswith input/output ports by way of a module signaling bus. Bus controllogic unit is coupled to the control bus portion of the backplane andinterfaces the control signals generated by the processor on the BCUwith various processor-controlled circuit components of a respectiveaccess module. One example of an access module having a modulararchitecture adaptable to the system of this invention is described inapplicant's U.S. Pat. No. 6,018,529 which is incorporated herein byreference. Details of the control and backplane signaling between theBCU and various access modules are provided below. Each access moduletype communicates a unique identification code to the BCU so that theBCU can automatically configure the system to provide access to thenetwork T1 and allocate bandwidth to the customer premises deviceconnected to that module.

Control of Quad FXS/DPO Modules

All aspects of a quad FXS/DPO access module are controlled via the BCU.Each individual port in the module is controlled independently of theothers. The aspects controlled and various options are: signaling modes(FXS Loop Start, FXS Ground Start, TR-08 Single Party, TR-08 UniversalVoice Grade, Tandem (E&M) and DPO); transmit Attenuation (0 to 9 dB); 2wire line impedance (600 ohms; 900 ohms, 600 ohms+2.16 uf; 900 ohms+2.16uf; and auto).

The wire line impedance can be auto discovered by the BCU which willinsert proper filter coefficients for a particular loop resistance. TheBCU also automatically sets the transmit and receive attenuation to 6 dBif the loop is short and 3 dB if the loop is long.

Control of Quad FXO Modules

All aspects of the quad FXO are controlled via the BCU. Each individualport in the quad port module is controlled independently of the others.The aspects controlled and various BCU options are: signaling modes (FXOloop start and FXO ground start); transmit attenuation (0 to 9 dB); andreceive attenuation (0 to 9 dB).

Control of Smart Access Modules

Smart access modules that require their own processor get provisioningthrough the BCU. The BCU communicates to the smart access modules viathe proprietary AAMPC2 protocol over which is passed access module type,timeslot, configuration, status and test information. The smart accessmodules that are supported are the Nx56/64, OCU DP, DSO DP, Dual DSU DP,and U-BRITE.

Alarm Control

The BCU controls the system alarms. System alarms are any event thatcauses an interruption of service. These include T1 failures, ringgenerator failure, and service affecting T1 tests. The BCU communicatesthese system alarms via the alarm relay contacts found on the PowerService Unit (PSU). The alarm relay contacts are referred to as audibleand visual alarm contacts. The alarm relay contacts are referred to asaudible and visual alarm contacts. The alarm relay contacts connect towire wrap posts on the backplane that may be connected to a variety ofnetwork alarm notification equipment. An alarm will cause the BCU toclose the alarm contacts and illuminate the alarm LED on the PSU frontpanel. Pressing the Alarm Cut Off (ACO) switch on the PSU front panelduring an alarm condition will cause the audible alarm contacts to open,thus silencing any connected notification equipment. Also, the PSU alarmLED will blink to indicate that the ACO switch has been pressed.

Customer Interface

The BCU provides the customer a terminal interface via an RS232 terminalinterface circuit 51 (FIGS. 10, 11) connected to the front panel DB9admin connector 34. The terminal interface uses a VT100 terminalemulation operation at 9600 baud. All configuration and control for theentire system 10 can be controlled through the terminal interface at theadmin connector 34. All DIP switch 46 settings can be overridden throughthe customer terminal interface.

Backplane Control

The BCU is responsible for generating the backplane signals that areused by all access modules in the system. The signals available at thecorresponding pins on are as follows:

Pin Name Function 1. CCLK+ Input, composite clock from office 2. CCLK−Input, composite clock from office 3. Dig GND Digital ground 4. MCLKOutput, 2.048 MHz system clock 5. Dig GND Digital ground 6. 20HZSYAInput, 20 Hz pulse aligned to ring generator on PSU 7. SPI_CLK Output,SPI clock 8. Dig GND Digital ground 9. SPISB Output, SPI control line“B” 10. SEL_PAU Output, control line used to select PSU card 11. T1R1-IInput, Network T1 Ring1 lead 12. T1T1-I Input, Network T1 Tip1 lead 13.T1R-O Output, network T1 Ring lead 14. T1T-O Output, Network T1 Tip lead15. Dig GND Digital ground 16. FT1R-O Output, Fractional T1 Ring lead17. FT1T-O Output, Fractional T1 Tip lead 18. FT1R1-I Input, FractionalT1 Ring1 lead 19. FT1T1-I Input, Fractional T1 Tip1 lead 20. ERX− Notused, No connect 21. −5 V −5 volt supply 22. +5 V +5 volt supply 23.+3.3 V +3.3 volt supply 24. FSYNC Output, 8 kHz T1 frame sync pulse 25.RPCM Input, Receive PCM data from backplane 26. TPCM Output, TransmitPCM data from network 27. Dig GND Digital ground 28. SPIOUT Input, SPIdata from access modules 29. SPIIN Output, SPI from BCU to accessmodules 30. SPISA Output, SPI control line “A” 31. SEL1 Output, Controlline used to select access module in slot #1 32. SEL2 Output, Controlline used to select access module in slot #2 33. SEL3 Output, Controlline used to select access module in slot #3 34. SEL4 Output, Controlline used to select access module in slot #4 35. SEL5 Output, Controlline used to select access module in slot #5 36. SEL6 Output, Controlline used to select access module in slot #6 37. ETX+ Not used, Noconnect 38. ETX− Not used, No connect 39. ERX+ Not used, No connect 40.Frame GND Frame ground

Customer Selectable Features (Daughter PCB DIP Switches)

The DIP switches 46 allow the customer to select form the followingsystem features: T1 type (B8ZS, AMI); T1 framing (ESF, SF, SLC-96 w/16bit alarms); CSU latching loopbacks enable/disable; bank timing mode;external timing (office composite clock); local timing, loop timing; andDS1 line build out (0 dB, −7.5 dB, −15 dB, −22.5 dB).

Front Panel LED's 47

T1 and Optioning LED's

Display Interpretation Network T1 Red, Main T1 and Red Alarm Yellow,Main T1 receiving yellow alarm from remote T1. Green, Main T1 normal(all alarms cleared) Fractional T1 Red, Fract T1 in Red Alarm Yellow,Fract T1 receiving yellow alarm from remote T1 Green, Fract T1 normal(All alarms cleared) Off, No channels allocated to Fract T1.

The system BCU includes a Field Programmable Gate Array (FPGA) 50 (FIGS.10 and 11) that is programmed to provide the following functionality forthe BCU: interface to the access modules via the SPI interface over thebackplane; timing generation in local, loop, and external timing modes;dialtone an ringback tone generation for Tandem 4ESS applications;multiplexing of backplane data with fractional T1 data; generation ofbit clock and byte clock for BCU front panel clock access; andgeneration of chip selects for T1 interface transceiver 42, FT1interface transceiver 43, front panel LED's 47, and switches 46.

Each access module slot 72 in the system chassis 11 can be selected bythe BCU over SPI interface 49. There are 7 different Card Selects (PSU &Slots 1-6) as well as two additional selects that are common to eachslot for selecting different registers/chips on a given access module.The following SPI timing diagrams are provided for reference only. Theactual timing is ultimately controlled by the processor 41 on the BCU.The SPI_IN side is very flexible and can adjust for clocking data in/outon either edge of the SPI_CLK depending on the needs of the accessmodule.

Power Service Unit

The power service unit (PSU) receives power (40-56 VDC) from the networkT1 (or optional AC power supply as described below) through a −48 VDCconnector and converts and conditions it for use by the system modules.Preferably, the PSU can provide −48 VDC, −24 VDC, −7 VDC, +3.3 VDC, +5VDC, and +12 VDC for use by the various system components. The PSU alsohas an integral 20 Hz ring generator for use by the telephone circuitsconnected to the FXO/FXS access modules.

Foreign Exchange Office and Foreign Exchange Subscriber Modules

The Foreign Exchange Office (FXO) and Foreign Exchange Subscriber (FXS)modules are used in the system provide analog voice extension. The twomodules may be used in a back-to-back configuration (FIG. 4( a) wherethe FXO interfaces to the central office switch, and the FXS interfacesto the customer's telephone. The more common configuration (FIG. 4( b)uses and FXS only, with the T1 interfacing directly to the CO switch(TR-08 mode). Up to six quad FXO/FXS access modules may be deployed inthe system allowing a maximum of 24 analog voice lines.

Four analog voice ports on the FXO/FXS access modules prove fourindividual connections to the switch or customer telephones. The Modulessupport standard loop start, ground start, and TR-08 signaling options.In addition to these signaling states, the FXS module supports E&M towink start, E&M to ground start, and immediate start signaling states.Direct Inward Dial (DID) applications are supported with the Dial PulseTerminate (DPT) and Dial Pulse Originate (DPO) functionality found onthe FXO and FXS, respectively.

A novel feature of the FXS access module is the automatic gainprovisioning option. This feature automatically adjusts the gain forshort and long loops, therefore expediting installation time anddecreasing provisioning errors. The auto gain feature may be overriddenas a software function via the craft interface.

For further flexibility, the FXS may be deployed on long loops, up to1200 ohm impedance. V.90 modems are supported by the FXS module.

Both of these voice access modules are hot swappable and accessible atall times. An individual access module may be replaced withoutdisrupting other units. The quad (4-circuit-per-access module) designensures a maximum of only four analog circuits are affected whenreplacing an access module.

Further detail about one embodiment of an FXS module usable in thesystem 10 is illustrated in FIGS. 12( a)-12 (c). Looking first at FIG.12 (a), the FXS module includes a quad subscriber line audio processingcircuit. (SLAC) which can be a conventional integrated circuit such asthe AM79Q021 from Advanced Micro Devices. The interrupt, card (module)ID, and battery register circuit (FIG. 12( a) allows the module toidentify itself to the BCU whereby the BCU will query the module forconfiguration information. Also include, again as shown on FIG. 12( a),are an address decoding section, a power monitor, and a module backplane(edge) connector 63.

FIGS. 12( b) and 12(c) show the four identical analog voice portcircuits 75(a)-(d) which provide the direct interface to four POTSdevices such as a telephone or modem (FIGS. 1 and 3). The corefunctionality of each voice port circuit 75 is provided by a subscriberline interface circuit (SLIC), such as an AMD 79489. Again, theconfiguration and operation of such circuits is conventional and wellknown to those of skill in the art.

FIG. 4( a) shows use of a system 10 with an FXS module on a customer endof the T1 and a second system 10 with an FXO module at the centraloffice end. FIG. 4( b 0 shows a system 10 with an FXO module at thecentral office end. FIG. 4( b) shows a system 10 with an FSX moduleconnecting the customer premises POTS telephone to the central officeswitch with the T1 operating in the TR-08 mode. FIG. 3 shows a pair ofsystems 10 connected to each other over a T1 to provide voice and datacommunications at each end.

Nx56/64 Access Module

The Nx56/64 access module is used in the system to provide aprogrammable data interface to various types of networking equipment.Some common applications for the Nx56/64 module include a high-speeddata interface for routers, audio broadcasting systems, andvideo-conferencing systems (FIG. 2). Designed to interface with standardV.35 DTE connectors on routers, bridged, codecs and switches, the systemNx56/64 module provides synchronous data that rates from 56 kbps to1.536 Mbps. To aid in setup and troubleshooting, the module providesV.54 local and remote loopbacks and built-in test patterns.

The Nx56/64 access module is configured through the BCU terminalinterface. The Nx56/64 module occupies slots 6 and 7 in the systemchassis 11. The physical interface to the module is on the rear of thesystem chassis in the form of a V.35 Winchester female connector (notshown).

Basic Rate-One Transmission Extension (U-BRITE) ISDN Access Module

Integrated services digital network (ISDN) communication systems enabletelephone service providers to supply multiple types of signalingchannels from a central office to a network T1 interface at a customerpremises site. An example of a reduced complexity extended distance ISDNcommunication network can comprise a T1 through which the networkprovider central office (CO) at one end of the T1 transmits and receivedsignaling traffic with respect to a customer premises communicationsdevice serviced by the system. The central office includes a centraloffice switch that contains a plurality of line termination circuits (orline access modules), each of which is coupled over a local loop(twisted tip/ring pair) to local customer site.

One embodiment of a U-BRITE access module that can be adapted for use inthe system 10 of this invention is described in applicant's U.S. Pat.No. 6,018,529, which is incorporated herein by reference. However, in apreferred embodiment of the system the U-BRITE access module, unlikethat disclosed in the '529 patent, will be “smart” (having its ownprocessor and will use a serial backplane interface compatible with BCUarchitecture disclosed herein.

AC Power Supply

Although the system 10 can be powered (via the PSU) from the centraloffice supplied −48 VDC, some customer applications warrant installationof a separate enclosure 80 and mounted to an exterior side wall of thesystem chassis 11, as shown in FIG. 8. A further option is to includebattery back-up for the system and, for convenience, mounting the systemchassis 11 directly to the hinged door 82 of the back-up enclosure 81.

As discussed above and illustrated in FIG. 13, many prior art batteryback-up systems utilize separate powering channels for supplying loadcurrent to an electronic system and supplying charging current to thebattery. The battery charge channel is generally designed to be constantcurrent or current limited and the power circuit is designed to haveenough power capability to fully power the load and charge the batterysimultaneously. However, if the load drawn by the electronic systemstatistically varies such that the average load over a 12 or 24 hourperiod is much less (half) than the peak load during the same intervalthen the power to charge the battery can be incorporated in thedifference between the peak and average load of the electronic system.Such is the case of a telecommunications system that provides (inaddition to voice and data signaling) ringing power to multiple voicephone lines. The ringing signal is sinusoidal (or trapezoidal) with a 20Hz frequency (for domestic USA) and is typically applied to each phoneline with a cadence (2 seconds on and 4 second off is the common).Further, the demand for ringing is highly statistical.

In addition to the power consolidation described above, if the separatecharge control circuitry shown in FIG. 13 can be folded into the powersupply circuit than the overall system cost and complexity is reducedresulting in a low cost, minimum size, maximum efficiency solution. Thenovel AC power supply and battery back-up system 200 shown in FIGS. 14and 15 provides such a solution and can be used to power the system 100of this invention.

Looking first at FIG. 14, a rectification and power conditioning section201 has an AC input connected to the 115 VAC utility network and asingle DC output connected to power the system 10. The DC output is alsoconnected to a battery 201 (which operates in a float mode) through anormally closed relay circuit 206. The battery 204 receives whateverpower is left over from the rectification and power conditioning stage201 as well as to the relay 206. The monitoring circuit 207 protects thebattery 204 by causing the relay 206 to open when the battery voltagegoes below a pre-set level. The telecommunication system 10 is designedto operate over the full battery voltage range (40V to 54V). Therefore,in one embodiment of the system 100, this pre-set level is 40 VDC. Inthe system 200 for FIG. 14, the battery 204 is connected directly acrossthe power supply output lines and no additional charge control isrequired.

FIG. 15 provides more detail about the AC power supply and batteryback-up system 200 of FIG. 14. The AC input is connected to a fullbridge rectifier 210 which provides a DC voltage across smoothingcapacitor 211. The voltage across the smoothing capacitor 211 issupplied to a flyback converter circuit comprising a flyback transformer212, a control circuit 213, a control circuit 213, a feed back circuit214, an electronic switch 215, and current sense resistor 216. Theflyback converter circuit has long been recognized as a beneficial powersupply circuit for its simplicity, low cost, and flexibility. Whenoperated in the so-called discontinuous mode (that is, the magnetic fluxin the flyback transformer begins each cycle at zero and ends each cycleat zero) and a fixed switching frequency the output power of the flybackconverter is limited to:

$P_{out} = {\frac{1}{2}*L_{p}*I_{pk}^{2}*f_{s}}$

In this analysis, Lp is the primary inductance of the flybacktransformer 212, Ipk is the peak current of the flyback primary, and fsis the switching frequency.

The discontinuous flyback can be applied to the AC power supply/batteryback-up system 200 using a low cost, industry standard pulse-widthmodulation (PWM) integrated control circuit (IC) 213, such as theUC3844. The discontinuous flyback AC/DC circuit is scaled to providepeak power to the telecommunications system 10, which on average drawsless than half peak power. During normal operation (AC power on, batteryfully charged and floating with maintenance charging current only), theduty cycle of the PWM signal at the output of control circuit 213 variesin response to the feedback circuit 214 so that the power MOSFET switch215 causes the output voltage measured at the junction of diode D1 andcapacitor C2 to remain at a nominal 54 VDC. If AC input voltage is lost,the battery 204 is already connected to the telecommunication system 10for immediate backup. When AC input voltage is restored, the outputvoltage measured at the junction of diode D1 and capacitor C2 is pulleddown to the battery voltage (which is now lower due to supplying powerto the telecommunication system). This output voltage is supplied to thefeedback input of control circuit 213 through feedback circuit 214. Inthis mode, the output power is limited by a peak current limit circuitintegral to the control circuit 213 IC, as sensed at current senseresistor 216. The telecommunication system 10 and the battery 203 thensplit the available power, with the telecommunication system 10 gettingwhat it needs for proper operation and the battery 204 getting theremainder for charging. The battery voltage (and thus the power supplyoutput voltage) climbs as it is being charged. It eventually increasesto 54V and then system comes out of power limit and again begins toregulate the output voltage using conventional PWM. No additional orspecial circuits are required to implement the battery charging andbackup function. The elimination of additional charging circuitry andoverhead power capacity reduces cost, and overall size, and increasessystem efficiency.

As discussed above, the invention of this system resides primarily inthe novel modular arrangement of conventional analog and digitalcommunication interface circuits and associated analog and digitalsignal processing components and attendant supervisory control circuitrythat controls the operations of such circuits and components.Consequently, the internal configuration of such circuits and componentsand the manner in which they are interfaced with the correspondingcustomer premises communication deices have, for the most part, beenillustrated in the drawings by readily understandable block diagrams andschematics, which show only those details that are pertinent to theinvention, so as not to obscure the disclosure with details which willbe readily apparent to those skilled in the art. Thus, the block diagramillustrations are primarily intended to show the major components of thesystem in a modular functional grouping, whereby the present inventionmay be more readily understood.

In addition, the mechanical features corresponding to the modulararchitecture of this system are illustrated generally in FIGS. 5-8.Although not essential to an understanding of the invention, additionalmechanical details about an embodiment of the system are available inapplicant's U.S. Pat. No. 6,597,576, issued Jul. 22, 2003 and entitled“Mounting Arrangements for Data Communication Devices”, the disclosureof which is incorporated herein by reference. However, the means bywhich the system modules mechanically engage and electricallyinterconnect with the system chassis and backplane are not limited tothose disclosed here. Those skilled in the art will recognize that avariety of conventional mechanical and electrical connectors andconnector systems can be used to implement the modular architecture ofthe system without departing from the scope of the invention.

The power supply and back-up system has been described with reference topowering an integrated T1 access system. However, those of skill in theart will recognize that the novel features of the power supply andback-up system can be readily adapted for use with a wide variety oftelecommunications equipment and other electronic devices that performcritical functions.

Although there have been described particular embodiments of the presentinvention of a Modular System for Connecting Multiple Customer PremisesVoice and Data Communications Devices to a T1 Data Line, it is notintended that such embodiment be construed as limitations upon the scopeof the invention except as set for in the following claims.

1. A scalable and configurable integrated T1 access system forconnecting multiple voice and data communication devices to a T1 line,comprising: a system chassis having a T1 line interface, a bankcontroller unit interface, a power supply unit interface, and multiplevoice and data communication device access module interfaces; multiplevoice and data communication device access modules connected to thesystem chassis using the multiple voice and data communication deviceaccess module interfaces, at least one of the voice and datacommunication device access modules having a processor for controllingfunctions of the respective voice and data communication device accessmodule on which the processor resides, wherein at least one of the voiceand data communication device access modules does not have a processor;a bank controller unit connected to the system chassis using the bankcontroller interface, the bank controller unit configured to provisioneach of the voice and data communication device access modules that havea processor, wherein functions of each of the voice and datacommunication device access modules that do not have a processor arecentrally controlled by the bank controller unit; and a power supplyunit connected to the system chassis using the power supply unitinterface, wherein the system chassis includes a rear panel, a series ofbackplane connectors arranged laterally along the rear panel forming thebank controller unit interface, the power supply unit interface, and themultiple voice and data communication device access module interfaces,and a series of slots for receiving the bank controller unit, the powersupply unit, and the multiple voice and data communication device accessmodules, and wherein the bank controller unit is designed to receiveunique identification codes from the multiple voice and datacommunication access modules connected to the system chassis that allowthe bank controller unit to automatically configure the system toprovide access to the T1 line and allocate bandwidth to the voice anddata communication devices.
 2. The system of claim 1, wherein: the T1line interface includes a DS1 interface, a network T1 interface, and afractional T1 interface; and the system chassis includes a customerterminal interface that allows a user to control the system using aVT100 terminal.
 3. The system of claim 1, wherein: the system can beconnected up to 24 analog telephones using one or more Foreign ExchangeSubscriber or Foreign Exchange Office access modules, a router orvideoconferencing system using a Nx56/64 access module, an ISDN terminaladapter using a U-BRITE access module, a DSU/CSU using a 4-wire DDSaccess module, or any combination thereof using one or more of themultiple voice and data communication device access module interfaces;the system can be connected to a PBX using a fractional T1 port includedwith the system; and the voice and data communication device accessmodule interfaces allow access modules to be removably connected to thesystem chassis.
 4. The system of claim 1, wherein: each of the multiplevoice and data communication device access module interfaces is designedto be connected to an access module that includes a circuit card havinga rearwardly projecting edge connector that mechanically andelectrically engages one of the series of backplane connectors when theaccess module is inserted into one or the series of slots included inthe system chassis; and each backplane connector includes pins thatprovide connections to system backplane power, serial peripheralinterface, and data buses used by the bank controller unit, power supplyunit, and voice and data communication device access modules connectedto the system.
 5. The system of claim 1, wherein the bank controllerunit includes a microprocessor connected to a T1 interface transceiver,RAM and FLASH ROM connected to the microprocessor using an octal latch,and a FPGA connected to the microprocessor, T1 interface transceiver,RAM, FLASH ROM, a backplane SPI interface, and a backplane datainterface.
 6. The system of claim 5, wherein the bank controller unitincludes a fractional T1 interface transceiver connected to themicroprocessor, firmware that provides all call control, test setup, andprovisioning for voice access modules connected to the system, a quadmultiplexer that can be used to download new programming to the FLASHROM, a circuit that provides watch dog and power reset functions, MCANoscillators that provide timing signals to the FPGA, and a compositeclock connected to the FPGA.
 7. The system of claim 1, wherein the powersupply unit is designed to receive power from the T1 line and to convertand condition the power for use by the multiple voice and datacommunication device access modules connected to the system chassis, andwherein the power supply unit comprise a ring generator for use bytelephone circuits connected to the voice and data communication deviceaccess modules that do not have a processor.
 8. A scalable andconfigurable integrated T1 access system for connecting multiple voiceand data communication devices to a T1 line, comprising: a systemchassis having a T1 line interface, a bank controller unit interface, apower supply unit interface, and multiple access module interfaces; atleast one dumb access module connected to the system chassis using atleast one of the access module interfaces, wherein each dumb accessmodule does not have a processor; at least one smart access moduleconnected to the system chassis using at least one of the access moduleinterfaces, each smart access module having a processor for controllingfunctions of the respective smart access module; a bank controller unitconnected to the system chassis using the bank controller interface, thebank controller unit configured to provision each smart access moduleconnected to the system chassis and to control centrally call functionsfor each dumb access module connected to the system chassis, wherein thebank controller unit is designed to receive unique identification codesfrom access modules connected to the system chassis that allow the bankcontroller unit to automatically configure the system to provide accessto the T1 line and allocate bandwidth to the voice and datacommunication devices; and a power supply unit connected to the systemchassis using the power supply unit interface, wherein the systemchassis a series of slots for receiving the bank controller unit, thepower supply unit, and the dumb and smart access modules.
 9. The systemof claim 8, wherein the power supply unit is designed to receive powerfrom the T1 line and to convert and condition the power for use by thedumb and smart access modules connected to the system chassis, andwherein the power supply unit comprise a ring generator for use bytelephone circuits connected to the at least one dumb access module. 10.The system of claim 8, wherein the at least one dumb access modulecomprises a voice access module.
 11. The system of claim 10, wherein theat least one smart access module comprises a data access module.
 12. Amethod for use in a scalable and configurable integrated T1 accesssystem for connecting multiple voice and data communication devices to aT1 line, comprising: inserting at least one dumb access module into arespective slot of the system, wherein each dumb access module does nothave a processor; inserting at least one smart access module into arespective slot of the system, wherein each smart access module has aprocessor controlling functions of the respective smart access module;inserting a bank controller unit into a slot of the system; inserting apower supply unit into a slot of the system; connecting the bankcontroller unit, the power supply unit, and the dumb and smart accessmodules to a chassis of the system; centrally controlling, via the bankcontroller unit, call functions for each dumb access module connected tothe chassis; provisioning, via the bank controller unit, each smartaccess module connected to the chassis; receiving, at the bankcontroller unit, unique identification codes from access modulesconnected to the chassis; and automatically configuring, via the bankcontroller unit, the system to provide access to the T1 line andallocate bandwidth to the voice and data communication devices based onthe unique identification codes.
 13. The method of claim 12, furthercomprising: receiving power from the T1 line; converting andconditioning the power, via the power supply unit, for use by the dumband smart access modules connected to the system chassis; and generatinga ringing voltage for use by telephone circuits connected to the atleast one dumb access module.
 14. The method of claim 12, wherein the atleast one dumb access module comprises a voice access module.
 15. Themethod of claim 14, wherein the at least one smart access modulecomprises a data access module.